2 BACKGROUND
Ontologies that are designed for reuse in a more gen-
eral form will help to frame our problem and provide
terms as a starting place for our design. In this section
we discuss different types of ontologies and the level
of concern they have for reuse to determine if and
where existing designs or ontologies can be reused by
a generic data collection ontology. We then focus on
ontology categorization in the context of where our
problem is best tackled keeping in mind our desired
high level view of data collection. Finally, we summa-
rize by drawing conclusions on existing designs and
what needs to be done in terms of defining generic
and reusable ontologies.
Ontological research has become widespread in
the design of information systems. Recently the de-
sire for ontologies to span and integrate different
views of a domain and even across domains has come
to fruition (Mascardi et al., 2010). The development
of these ontologies provides the opportunity for sys-
tems to integrate and become interoperable allow-
ing for information sharing (Herre, 2010) (Mascardi
et al., 2010). In this case an ontology acts as a
bridge between systems unifying information (Herre,
2010) and allowing systems to communicate through
the ontology using their standard language and mes-
sage passing techniques. Unifying data allows the
key components of one or more domains to be cap-
tured and shared among ontologies that further define
a particular domain. The ability for an ontology to
capture a particular domain is related to its viewpoint
of the world, each ontology imposes a particular view
which defines its ability to share information. This
viewpoint is therefore what we are concerned with.
2.1 Classifying Ontologies
Domain level ontologies are ontologies that seek to
capture a shared conceptualization of a particular do-
main. These ontologies contain domain specific terms
and may only be linked to a specific application
(Roussey et al., 2011). Domain ontologies are im-
portant in that they describe the type of data we seek
to capture but for our problem we may not assume
any particular domain to capture data from. A do-
main level ontology, however, could represent the end
product for a system using our ontology.
A core ontology is linked to a particular domain
but has the advantage of providing several view-
points relating to different user groups (Roussey et al.,
2011). Core ontologies are often the result of several
domain level ontologies mapped together (Roussey
et al., 2011). Core level ontologies represent a higher
level of term generality as they seek to span and
provide definitions for a wider domain or domains.
From our perspective core level ontologies are cer-
tainly closer but still maintain the requirement of do-
main specific content within them and cannot generi-
cally be applied to any domain.
Foundational or upper level ontologies can be
summed up with the following definition: a founda-
tional ontology seeks to provide definitions and terms
that are general to all domains. (Mascardi et al.,
2007). They serve as a building block for future on-
tologies by enabling reuse since they define common
terms that will be contained by domain level ontolo-
gies. The goal of an upper level ontology is to avoid
the redefinition of common terms to allow for easier
and consistent reuse of defined terms. In other words
they provide a single agreed upon definition of terms
(Mascardi et al., 2010) (Roussey et al., 2011). More
importantly however is the fact that they are designed
to support all domains which differs from core or do-
main ontologies that only define terms for their par-
ticular domain, likely choosing specific (overloaded)
definitions over general definitions (Roussey et al.,
2011).
A mid level ontology seeks to provide a bridge
between an upper ontology and a domain level on-
tology by providing terms that will be common to
several domain level ontologies or areas of domain
level ontology (Ceusters and Smith, 2015). There-
fore mid level ontologies serve a similar purpose to
the upper level ontology by preventing term redefi-
nition and providing consistent relationships but at a
more specific level. This has several advantages in
addition to avoiding redefinition, firstly, it provides
a common understanding between derived ontologies
through similar terms, structures and relations, sec-
ondly, it provides a more streamlined starting place
for those new to the construction of ontologies by pro-
viding terms more closely related to their domain than
that of upper level ontologies. In terms of an ontology
category hierarchy the mid level ontology falls in the
middle with domain level ontologies extending mid
level ontologies and mid level ontologies extending
upper level ontologies. The full hierarchy can be seen
in fig. 1.
One might then wonder why the work put into
the development of upper level ontologies has not re-
sulted in a common ontology that is shared among
all domain level ontologies. One particular reason for
this is down to implementation, where languages im-
plemented by computer scientists are based on set the-
ory that captures abstract content well but does not
capture the concrete objects and their relationships
well enough to be completely generic (Degen et al.,